Mixer, especially for synthetic materials



y 1966 FRIEDRICH'WALTER HERFELD 3,250,519

MIXER.

Filed July 6, 1962 ESPECIALLY FOR SYNTHETIC MATERIALS 5 Sheets-Sheet l INVENTOR. F73" olns 6 Iva/h1- Her/e loL BY y 1966 FRIEDRICH-WALTER HERFELD 3,

MIXER, ESPECIALLY FOR SYNTHETIC MATERIALS 5 Sheets-Sheet 2 Filed July 6. 1962 23 Fig.9 5%

1955 FRlEDRlCH-NALTER HERFELD 3,250,519

MIXER. ESPECIALLY FOR SYNTHETIC MATERIALS Filed July 6, 1962 5 Sheets-Sheet a Fig. 13 45 1 29 Fig/ab a i INVENTOR. flair/c4 HI/fer HFIfQ l9! y 1966 FRIEDRICH'WALTER HERFELD 3,

MIXER, ESPECIALLY FOR SYNTHETIC MATERIALS 5 Sheets-Sheet 4 Filed July 6, 1962 y 1966 FRIEDRICH-WALTER HERFELD 3,250,519

MIXER, ESPECIALLY FOR SYNTHETIC MATERIALS Filed July 6, 1962 5 Sheets-Sheet 5 INVENTOR. mind-1,44 64- ha United States Patent O 3,250,519 MIXER, ESPECIALLY FOR SYNTHETIC MATERIALS Friedrich-Walter Herfeld, Neuenrade, Westphalia, Germany, assignor to Vaterland-Werk Friedrich Herfeld Siihne, Neuenrade, Westphalia, Germany Filed July'6, 1962, Ser. No. 208,028

Claims priority, application Germany, Apr. 13, 1962,

V 22,339 3 Claims. (Cl. 261-93) The present invention relates to a mixer, especially for synthetic materials and also for thechemical, pharmaceutical, and food industry, and in particular concerns a mixer comprising a mixing container with a motor driven mixing cross.

Mixers for synthetic material are known which comprise a mixing container having a pivot mounted along a circular line on the bottom of the container, while the motor driven mix-ing tool is provided with correspondingly arranged studs cooperating with the stationary pivot on the bottom of the container.

Furthermore, mixers are known the mixing cross arms of which work in one direction only with the cutting edge.

Also mixing devices have been suggested which employ a mixing tool having mixing arms in groups of four arranged in a plurality of horizontal planes. 7

In addition thereto, mixers for synthetic material have become known in which the mixing member rotating at high speed heats up the material to be mixed inasmuch as a portion of the mixing energy is transformed into heat energy. For reducing the heating period of the mixture of synthetic material and of the mixing container, a heating jacket has been employed for mixing containers which is employed either by itself or in combination with the high-speed rotating mixing member. For purposes of cooling the mixed material, a cooling medium may be passed through the jacket.

For purposes of cooling the mixed material in a mixer for synethetic material, a device has heretofore been employed which, by .means of a conduit, continuously withdraws the mixed material at the lower end of the mixing container or of a separate container and passes the withdrawn material through a cyclone separator in which the mixed material is separated from air and then is again passed into the starting container into which also cooling air may be introduced. This known cooling device is rather expensive and comprises too many parts.

It is an object of the present invention toprovide a mixer of the above mentioned general type in which the introduction of heat through a heating jacket will not be necessary and in which the friction between the mixing cross and the material to be mixed will furnish the required heat.

It is another object of this invention to provide a mixer as set forth in the preceding paragraph, which is relatively simple in construction and highly efiicient and economical.

It is also an object of this invention to provide a mixer as set forth above which makes it possible in a relatively short time to cool the mixing material subsequent to the heating process.

It is a further object of this invention to provide a mixer for synethetic material which has a boiler-like mixing container and a mixing member arranged above the bottom of the mixing container, in which the heating as well as the cooling of the mixed material may be carried out in a minimum of time and at low costs.

These and other objects and advantages of the invention will appear more clearly from the following specifica- 2 tion in connection with the accompanying drawings, in which:

FIG. 1 is a section through a mixer according to the present invention.

FIGURE 1a represents a section along the line 1a1a of FIGURE 1. 4 I

FIGURE 1b is a section through the sight glass in the lid of the mixer drawn at enlarged scale.

FIG. 2 shows a top view of the mixer of FIG. 1 with the lid of the latter removed.

FIG. 3 is a section taken along the line III-III of FIG. 2, but on a larger scale than that of FIG. 2.

FIG. 4 is a section along the line IVIV of FIG. 2, but likewise on an enlarged scale.

'FIG. 5 illustrates the setting of the mixing arms. FIG. 6 is a section along the line VI-VI of FIG. 5, but on an enlarged scale.

, FIG. 7 is a section along the line VII-VII of FIG. 5, likewise on an enlarged scale.

FIG. 8 illustrates the setting of the upper mixing arms. FIG. 9 is a section along the line IX-IX of FIG. 8, also on an enlarged scale. I

FIG. 10 is a section along the line XX of FIG. 8,

but on an enlarged scale.

FIG. 11 shows a modified container with tapering edge. I

FIG. 12 illustrates partly in section the cooling of the bottom and the side wall of the container. 1

FIG. 13 illustrates a modification of the lower portion of the container and the flanged-on motor, the seal of the shaft for the mixing cross relative to the motor housing likewise being shown.

' FIG. 14 shows a modification of the seal for the shaft of the mixing cross in the container bottom. a

FIG. 15 represents a still further modification of the seal for the shaft of the mixing cross.

FIGS. 15a and 15b illustrate modificationsin. the twisting of the mixing arms. FIG. 16 represents a vertical section through a modilied mixing container. v

FIG. 17 is a section taken along the line XVII-.-XV I I of FIG. 16.

FIG. 1-8 is a section through a tube employed .in connection with the apparatus according to thev invention.

FIG. 19 likewise represents a section through a tube with a guiding surface and shows the arrangement of the tube with regard to the container wall.

FIG. 20 illustrates a further modification of an air tube.

General arrangement The present invention concerns a mixer construction especially for synthetic materials, which has a motor driven mixing cross and is characterized primarily in that each two mixing arms located opposite to each other with regard to the shaft for the mixing cross are located at re- ,The mixing arms located in one plane are offset by in the direction of rotation thereof with regard to the mixing arms in the second plane.

According to the present invention, two oppositely located mixing arms, i.e., the two upper mixing arms operate in the main Working direction-mixing and heating processwith blunt, gable-like end faces, whereas in the opposite direction-cooling operation-they operate with relatively sharp back edges. The front and back surfaces The driving motor for the shaft carrying the mixing cross is directly adjacent the bottom of the mixing container so that expensive transmission means between motor and shaft for the mixing cross will be avoided. The mixing container is furthermore tiltable about a horizontal axis and may be arrested at random in its tilted position. I

Preferably, the motor is so arranged on the container bottom that a considerable balance of the weight between the container with contents and the motor will be obtained and/ or by controlling the container jacket cooling. The

mixing process as well as the temperature control can in this way easily be efiected. Moreover, when reaching a desired temperature of the mixing material, the direction of the driving motor for the mixing tool may be reversed, i.e., may be rotated in opposite direction for the cooling process or for specific mixing problems.

The mixing container has .a wall cooling system and bottom cooling system which, if so desired, may be con trolled in unison or independently for efiicient operation. For purposes of sealing .the shaft of the mixing cross with regard to the motor, said shaft is provided with a centrifuga'l disc fixedly connected to said shaft and arranged in an intermediate chamber between the container base and the motor flange which latter is equipped with lateral outlets. For purposes of further sealing the container bottom relative to the mixing cross shaft at the level of the container bottom, the mixing cross shaft is surrounded 'by two metallic rings or flanges between Whichone or more elastic seals are provided,for instance seals of synthetic material such as polyvinyl chloride, asbestos and the like. If desired, a slide ring seal of any known type may be employed.

A particularly advantageous arrangement for heating and cooling the mixed material'in a minimum of time and at low cost will be obtained when, with a mixer of the above mentioned type, at least one tube is provided which is arranged in the mixing chamber and the lower edge of wh1ch extends directly above or below the mixing member and is adapted to convey warm or cold air into or below the material to be mixed. Preferably, but not necessarily, the invention is employed where a heating-up of the material to be mixed is already effected due to the design of the mixing member and/or in view of the speed of rotation thereof.

In connection with the rotary movement of the mixing member, care is to be taken that the Warm or cold air will intimately contact the material to be mixed; This arrangement is advantageous inasmuch as the drying of the mixed material may favorably be influenced by the fact that the introduced warm air has a low humidity content.

It is furthermore of great importance that the introduced air forms an air cushion below the material to be mixed. This cushion may be so designed that it takes up the space of the mixing member more or less completely.

'A-t peaks of energy requirement for the mixing member, namely when the mixer starts and at a certain stage of end has a flat mouth.

the load, as for instance when the material is being plasticized, addition of liquids, and the like, it is, therefore,

possible to introduce into the mixing chamber such a quantity of air that the mixing member will operate in the air cushion in which, however, also a certain quantity of material to be mixed is present. The resistance due to the smaller quantity of material to be mixed will then permit the mixing member to operate at low energy requirement which may be less than 50% of the heretofore necessary energy requirement.

Another important factor is seen in that the mixing material when moving around the longitudinal axis of the container will continuously contact the tube or the tubes. When employing a plurality of tubes, the same may be arranged symmetrically with regard to the axis of rotation of the mixing member. The tubes may be connected to the container lid or they may be mounted on a tubular elbow connected to the container wall. The design of the tubes may be so selected that'their lower In order to obtain a radial change in direction or to influence the movements of the material being mixed with regard to the tubes or the mixing member, the tubes may be provided with guiding surfaces and/or with attached guiding plates. Furthermore, the tubes may be rotatable about their longitudinal axes.

In order to improve the effect of blowing air below the material to be mixed, it is advantageous to employ a disc which is preferably round and is so mounted on the mixing member that it will carry out the same revolutions as the mixing member-and parallel to the plane of movement thereof. A disc of this type preferably has a diameter of approximately 50% of the inner diameter of the mixing containen' However, the disc must not cover up the opening of the blowing tube inasmuch as this would affect the entire effect. In view of the high speed of rotation of the mixing member of the mixer for synthetic material, the vertical rotation of the material to be mixed is effected by the fact that, due to the centrifugal force, said material is driven toward the wall of the mixing container. As a result thereof, a central free space in the container is obtained through which the air may escape from below the material to be mixed into the space above said material. This, however, is prevented by the above mentioned disc according to the invention.

In particular, with relatively heavy material to be mixed, and at low filling of the container, the above mentioned disc has proved highly advantageous in bringing'about the above mentioned effect of the air. cushion.

In addition thereto, the said disc is adapted to relieve the mixing member when mixing material is involved which is difficult to mix, is plastic or paste-like. It will be appreciated that in this instance the disc helps in carrying the material to be mixed.

Strtuctural arrangement Referring now to the drawings in detail and FIG. 1 thereof in particular, the mixer shown therein comprises a container 10 below which there is arranged a motor 1']. for driving the mixing cross 12 in said container 16. The container 10 has vertical side walls 16a and a nearly horizontal bottom 10b through whhich shaft 13 extends 10 or to the base '30 thereof. The motor 11 is provided with a groove 3-1 engaged by lateral arms 32 having, their ends bent at a right angle so as to form arms 36. These arms 33 are by means of bolts 35 journalled in walls 34.

One of the arms has an extension 36 and carries a pivot 37 adapted to have its free end engage bores 38 in a wall 34 in conformity with the tilted position of container 10. In this connection, it may be mentioned that the container is tiltable about pivots 35. Container 10 is located above the pivots 35 while at least the majorportion of motor 11 is located at a level Substantially below said pivots.

The mixing cross 12 has two upper arms 15, 16 located in the same vertical plane (see FIG. 2) and also in the same horizontal plane :1 (see FIG. 1). In addition thereto, the mixing cross 12 has two lower arms 17, 18 (FIGS. 1 and 2) which are located in a second vertical plane b perpendicular to the said vertical plane of arms 15 and 16. The two lower arms are also located generally in a second horizontal plane v below horizontal plane 1:. The upper arms 15, 16 are vertically spaced from the lower arms '17, 18 by a distance which amounts to approximately one-tenth to one-half of the container height. The mixing arms 15, 16 have a cross section of a contour shown in FIG. 3. As will be seen therefrom, the front side of said mixing arms 15, 16, i.e., that side which, during the mixing operation is located in the direction of rotation, is formed by two end faces 19, 20 which are gable-shaped. The mixing arms are furthermore provided with two substantially parallel surfaces 21, 22, whereas the back side of arms 15, 16 is formed by surfaces 23, 24 tapering with regard to each other in outward direction. As will be evident from the drawings, the surfaces 19, 21 include therebetween an angle a which is greater than the angle ,8 confined by the surfaces 23, 24. The surfaces 19, 20 and 23, 24 are located symmetrically with regard to a common central plane 25.

The lower mixing cross arms 17, 18 have a fiat bottom side (FIG. 4) and an intermediate surface 27 parallel thereto. The end face 28, which during normal rotation of the mixing cross is located in front, forms with the bottom side 26 an angle y. The angle 7 is greater than the angle a formed by the inclined back side 29 with the bottom side 26.

The arms 17, 18 are twisted from their inner end, i.e. from that end facing the mixing cross shaft 13, and this twist extends about the longitudinal axis of said arms to the outer end thereof. While at the level of line Vl VI in FIG. 5 the mixing arm 18, for instance, has the position shown in FIG. 6 with regard to a horizontal 49a,

it will be seen from the drawing that the same arm at thelevel of line VII-VII of FIG. 5 has a position as it is illustrated in FIG. 7. The bottom side 26 forms an angle 5 with the horizontal 40a. The arms 15, 16 may be twisted in a similar manner. At the level of the line IX IX in FIG. 8, the central plane (FIG. 9) of arm 15 is horizontal and with regard to the surfaces 19, 2t and 23, 24 is substantially symmetrical. At the level of line XX in FIG. 8, arm 15 has a twist (FIG. 10) at which the central plane 25a forms an angle 6 with the horizontal 40b.

FIG. 11 shows an advantageous embodiment of a container according to the invention in which the upper marginal section 180 tapers inwardly whereby the mixing material circulating in thedirection of the arrows A does not permit the formation of dead zones where residues could settle.

FIG. 12 shows a section of a container wall 10d and also shows a section of a bottom 10e. These walls confine therebetween the cooling chambers 41, 42 which may selectively be put into operation.

Container 11) is provided with a device 43 (FIG. 1) which is a kind of thermostat adapted in response to a certain temperature of the mixing material having been reached, to automatically reverse the direction of rotation of the drive motor 11 for the mixing cross 12. Simultaneously, there may be provided a speed control and a signalling device for the cooling water control or an automatic cooling water control. The motor is sealed with regard to the mixing container. To this end, according to the embodiment of FIG. 13, the base 30 has connected thereto the flange 31 of motor 11 while an intermediate chamber 44 is formed. This intermediate chamber has discharge passages 45 provided in the flange 31. Shaft 13 of the mixing cross has at the level of the intermediate space 44 a plate 46, the rim of which is-preferably downwardly bent at 46a where it extends around an elevation of the flange. If the mixing material should escape from container 10 and pass along shaft 13, it will be caught by the dish-shaped plate 46 tightly keyed to shaft 13 and will be thrown outwardly to pass through discharge openings 45 from the intermediate chamber 44. By providing a corresponding pan below passage 45, the leak-out substance may be caught. The dish-shaped plate 46 may, if desired, also have a conical shape.

For purposes of sealing the container 16', the embodiment shown in FIG. 14 has proved advantageous. Ac cording to this embodiment, at the level of the mixing cross shaft 13 there is provided in the bottom 1% a sleeve 47 having an inner bore 48. Said bottom 1% is formed by the two wall portions 100, 101' and the intermediate cooling chamber 102. A metal ring 49 which is softer than shaft 13 is inserted into bore 48. Between said ring 49 and flange 50 of the sleeve there are inserted two elastic seals 51, 52. These seals may consist of any suitable synthetic material such as polyvinyl chloride or asbestos or the like. 1

A further seal of the container 10 may be effected by the embodiment of FIG. 15 according to which the mixing cross shaft 13 carries an annular disc 53 which has its outer marginal portion 54 bent downwardly. While the section 55 is resiliently bent near shaft 13 and presses said marginal portion against sleeve 47, the edge 56 of the outer marginal portion grinds itself into the sleeve whereby a good seal will be obtained.

While for purposes of mixing and simultaneously heating the mixing material, the mixing cross 12 is rotated in the direction of the arrow 63 (FIG. 2) so that the respective steeper end faces 19, 20 and 28 of the mixing arms will be located in front in the direction of rotation, and the less steeply inclined surfaces 24, 25 and 29 will form the back sides when looking in the direction of rotation. t is possible forpurposes of cooling, to reduce the speed of rotation of the mixing cross and to reverse the direction of rotation of said mixing cross. In this way, the less inclined surfaces will form the front surfaces of the mixing arms when looking in the direction of rotation. As indicated above, the container 10 may be tilted.

If necessary, the twisting of the mixing arms may be effected in a different direction than is illustrated in FIGS. '5 and 10 so that the angles 6 and e in FIGS. 7 and 10 will be located below the horizontal 48a, 40b (see FIGS. 15a and 15b).

Referring now to the modification illustrated in FIGS.

16 and 17, it will be noted that the mixing member generally designated 103 is arranged in the boiler-shaped mixing container 101 which is adapted to be closed by a lid 102. The said 'mixing member 103 comprises a mixing blade 104 arranged above the container botom, and a further or second mixing blade 105 which is located at a somewhat higher level. The mixing member 103 is driven by a motor 106 and is adapted in view of its high speed of rotation to heat up the material to be mixed. The container 101 rests in a manner known per se on a base 107 which is mounted on a rotatable frame 108. Frame 1198 is tiltable about bolts 169 and can be arrested in its respective position by bolt 110. In FIG. 16 disc 105a is positioned above the upper blade 105.

One or a plurality of tubes 111 adapted to convey warm or cold air extend into the mixing contaainer 101. The said tubes 111 may either be connected to the lid 102 or may be connected to an elbow member 112 which is mounted in the wall 101a of the container. Selectively hot air or cold air may through conduits 113 be introduced into the tubes while the discharge of the air will be effect ed in .a manner described further below. As will be seen from the drawings, the free ends 111a of the tubes extend downwardly directly above the mixing member, i.e. above the mixing blade 105. A plurality of tubes 111 are advantageously arranged symmetrically with regard tothe axis of rotation of the mixing member as indicated in FIG. 17 according to which the tubes are arranged so as to form the corners of a triangle. However, also any other arrangement may be suitable.

Preferably, the tubes 111 have over the major portion of their length an annular flattened or elliptical cross section and at their lower end end in a flattened month 114 as shown in FIG. 18.

The tubes 111 may also have a cross sectional restriction at their lower end in order to thereby accelerate the air being discharged. The tubes 111 may furthermore be provided with a guiding surface or an attached guiding blade 115 which may be of curved shape. In view of this design of the tube 111, a change in the direction of the material to be mixed radially of the container is obtained in such a way that the said material will be conveyed toward the central axis of the container or in opposite direction. Particularly when the tubes are rigid and are connected to the lid (FIG. 16), the tubes may be rotatable about a longitudinal axis, by means not shown, so that the extent and the direction of the change in the movement in the said radial direction of the material to be mixed will be adjustable. To this end the tubes may have spiral rib means 118 theron. If desired, tubes may also be provided with smaller discharge openings 116 as illustrated in FIG. 20, said openings being provided laterally in the tubes. Thus, in addition to the lower discharge openings 117, there are provided openings through which the air jet may be discharged also in radial direction of the tube in order to heat up the material to be mixed or to cool the same. In view of the discharge of the warm or cold air through the openings 117 at the lower end and in axial direction of the tubes, it is possible to create a more or less strong air cushion at the level of the mixing member 103. It is in this air cushion that the mixing member may rotate at low energy requirement when the material to be mixed due to warming up, plasticizing or during the starting of the machine has reached a condition which would necessitate a high power requirement.

For purposes of improving the effect, the disc 105a is mounted directly on the mixing member and screwed together with the latter to the driving shaft 103. Air from below of the material to be mixed will be prevented to a greater extent from escaping when said material during the operation of the machine is driven against the wall of the container. Furthermore, this disc may aid in supporting the material to be mixed and thereby relieve the mixing member.

It is, of course, to be understood that the present invention is, by no means, limited to the particular constructions shown in the drawings, but also comprises any modifications within the scope of the appended'claims.

What I claim is:

1. In a mixer, especially for mixing synthetic materials, a container for receiving the material to be mixed, a reversible motor beneath said container, a shaft drivingly connected to said motor and extending upwardly through the bottom portion of said container, a first pair of mixing arms in said container connected to and respectively located on opposite sides of said shaft, a second :pair of mixing arms in said container connected toand respectively located on opposite sides of said shaft but vertically spaced from said first pair of mixing arms, the longitudinal edges of the arms of one of said pairs of mixing arms being tapered in such a Way that the angle on the front edge of each of the arms when looking in the normal direction of rotation of said last mentioned pair of arms is greater than the angle on the rear edge of each of the respective arms, and thermostatic means arranged in said container and adapted for being operatively connected to said motor for reversing the direction of rotation of said motor and thereby of said shaft in response to a certain temperature within said container.

2. A mixer, especially for mixing synthetic materials, which comprises: a container for receiving the material to be mixed, a rotatable shaft extending through the bottom of said container, mixing arms mounted on said shaft Within said container, a disc mounted on said shaft above said mixing arms, a plurality of tubular means respectively having an inlet and an outlet, at least the major portion of said tubular means being arranged within said container and having their outlets extending to points directly above said disc, the outer diameter of said disc being less than the distance between the discharge ends of said tubular means, means to connect the inlets of said tubular means with air of a desired condition for selectively heating up and cooling the material to be mixed in 'said container, said tubular means being arranged symmetrical- 1y with regard to the axis of rotation of said shaft and the center of said disc.

3. A mixer accordingto claim 2 in which each said tubular means includes means operable to divert material radially of the container in response to movement of the material over said tubular means in the circumferential direction of the container.

References ited by the Examiner UNITED STATES PATENTS 117,446 7/1871 Mulholland 259-134 1,409,112 3/1922 Jones 259-134 1,521,873 1/1925 Dunham 259-107 1,737,624 12/1929 Thomson 261-93 1,760,058 5/1930 Hennebutte et al. 261-93 2,187,746 1/ 1940 Lefevre 261-87 2,193,934 3/1940 Moores 261-87 X 2,246,560 6/1941 Weinig et al. 261-93 2,513,254 6/1950 Savage 2.59-107 2,646,237 7/1953 Hinesman 248-13 2,757,909 8/1956 Wayne 259-107 2,801,083 7/1957 Balassa 261-93 X 2,836,589 5/1958 Allen et al 261-93 X 2,926,002 2/ 1960 Spielvogel 259-108 2,945,634 7/1960 Beck et al 259-107 3,024,010 3/1962 Sperling 259-134 3,046,584 7/1962 Wepfer 15-22 3,064,950 11/1962 De Laria 259-108 3,133,976 5/1964 Gross 261-93 X 3,139,917 7/1964 Elmore 259-107 X FOREIGN PATENTS 1,060,317 11/1953 France.

HARRY B. THORNTON, Primary Examiner.

CHARLES A. WILLMUTH, Examiner.

T. R. MILES, E. L. ROBERTS, Assistant Examiners. 

1. IN A MIXER, ESPECIALLY FOR MIXING SYNTHETIC MATERIALS, A CONTAINER FOR RECEIVING THE MATERIAL TO BE MIXED, A REVERSIBLE MOTOR BENEATH SAID CONTAINER, A SHAFT DRIVINGLY CONNECTED TO SAID MOTOR AND EXTENDING UPWARDLY THROUGH THE BOTTOM PORTION OF SAID CONTAINER, A FIRST PAIR OF MIXING ARMS IN SAID CONTAINER CONNECTED TO AND RESPECTIVELY LOCATED ON OPPOSITE SIDES OF SAID SHAFT, A SECOND PAIR OF MIXING ARMS IN SAID CONTAINER CONNECTED TO AND RESPECTIVELY LOCATED ON OPPOSITE SIDES OF SAID SHAFT BUT VERTICALLY SPACED FROM SAID FIRST PAIR OF MIXING ARMS, THE LONGITUDINAL EDGES OF THE ARMS OF ONE OF SAID PAIRS OF MIXING ARMS BEING TAPERED IN SUCH A WAY THAT THE ANGLE ON THE FRONT EDGES OF EACH OF THE ARMS WHEN LOOKING IN THE NORMAL DIRECTION OF ROTATION OF SAID LAST MENTIONED PAIR OF ARMS IS GREATER THAN THE ANGLE ON THE REAR EDGE OF EACH OF THE RESPECTIVE ARMS, AND THERMOSTATIC MEANS ARRANGED IN SAID CONTAINER AND ADAPTED FOR BEING OPERATIVELY CONNECTED TO SADI MOTOR FOR REVERSING THE DIRECTION OF ROTATION OF SAID MOTOR AND THEREBY OF SAID SHAFT IN RESPONSE TO A CERTAIN TEMPERATURE WITHIN SAID CONTAINER.
 2. A MIXER, ESPECIALLY FOR MIXING SYNTHETIC MATERIALS, WHICH COMPRISES: A CONTAINER FOR RECEIVING THE MATERIAL TO BE MIXED, A ROTATABLE SHAFT EXTENDING THROUGH THE BOTTOM OF SAID CONTAINER, MIXING ARMS MOUNTED ON SAID SHAFT WITHIN SAID CONTAINER, A DISC MOUNTED ON SAID SHAFT ABOVE SAID MIXING ARMS, A PLURALITY OF TUBULAR MEANS RESPECTIVELY HAVING AN INLET AND AN OUTLET, AT LEAST THE MAJOR PORTION OF SAID TUBULAR MEANS BEING ARRANGED WITHIN SAID CONTAINER AND HAVING THEIR OUTLETS EXTENDING TO POINTS DIRECTLY ABOVE SAID DISC, THE OUTER DIAMETER OF SAID DISC BEING LESS THAN THE DISTANCE BETWEEN THE DISCHARGE ENDS OF SAID TUBULAR MEANS, MEANS TO CONNECT THE INLETS OF SAID TUBULAR MEANS WITH AIR OF A DESIRED CONDITION FOR SELECTIVELY HEATING UP AND COOLING THE MATERIAL TO BE MIXED IN SAID CONTAINER, SAID TUBULAR MEANS BEING ARRANGED SYMMETRICALLY WITH REGARD TO THE AXIS OF ROTATION OF SAID SHAFT AND THE CENTER OF SAID DISC. 